There is a well established use of overlay content superimposed over channel content, such as a television network identification over the TV video stream. FIG. 6 is an illustration of a conventional media gateway 601 that is part of a larger data network 603 over which video streams and overlay content are transported. It should be understood that the media gateway 601 is included in the network 603 and not apart therefrom. The data network 603 includes 1st through Nth servers 615 servers, each server being capable of storing video image data and overlay content data.
The media gateway 601 is configured to include a decoder channel 605, an overlay channel 607, an overlay renderer 611, a mixer 613, and an encoder channel 609. In the conventional network illustrated in FIG. 6, a single server, for example the 2nd server 617 transmits overlay content to the overlay channel 607. The overlay content includes different types of overlay including text, graphics, or combined texts and graphics, static graphics, animated text, and the like. The overlay content received through the overlay channel 607 is passed to the overlay renderer 611 where the overlay content is decoded into “YUV” format, a color space known in the art to include measurements of luminance, red chrominance, and blue chrominance. The video mixer 613 then receives the rendered overlay content in YUV format from the renderer 611.
Approximately concurrently, the decoder channel 605 transports a decoded video stream (also in YUV format) to the mixer 613. As is known in the art, the mixer 613 then mixes the decoded video stream and rendered overlay content into a mixed stream. The mixed stream is then encoded and transported to the network via the encoder channel 609.
There are drawbacks with the above-described conventional media gateway and associated network. Initially, if the 2nd server 617, for example, transmits the overlay content over the single overlay channel 607, if the overlay content is a combination of graphics and text, the graphics and text components can only be used in a combined manner, and only with a single video stream at a time. That is, the overlay content cannot be split up into component text and graphics, and cannot be distributed to multiple encoded mixed streams simultaneously. An additional drawback in the conventional art is that even if overlay content data is intended to be used repeatedly in multiple encoded mixed streams, a single stream at one time, the gateway 601 does not store the overlay content thereby requiring the 2nd server 617, for example, to transmit the same overlay content every time the overlay content is to be mixed with a different video stream. This situation results in significant overhead costs, including using excessive gateway/processor and bandwidth resources.